Liposome‐encapsulated hemoglobin (HbV) transfusion rescues rats undergoing progressive lethal 85% hemorrhage as a result of an anti‐arrhythmogenic effect on the myocardium

Abstract

Liposome‐encapsulated hemoglobin vesicles (HbV) can serve as a blood substitute with oxygen‐carrying capacity comparable to that of human blood and lethal hemorrhage is associated with lethal arrhythmias. To investigate the resuscitation effect of HbV on lethal hemorrhage and anti‐arrhythmogenesis, we performed optical mapping analysis (OMP) and electrophysiological study (EPS) in graded blood exchange (85% blood loss) in the rat model. We also measured cardiac autonomic activity, as assessed by heart rate variability (HRV), and changes in plasma norepinephrine and left ventricle ejection fraction (LVEF) by echocardiography. Pathological study on Connexin43 was performed. A 5% albumin (ALB group), washed rat erythrocytes (wRBC group), and HbV (HbV group) were used as a resuscitation fluid. The survival effects over 24 hours were examined. All rats died in the ALB group, whereas almost all survived for 24‐hours period in wRBC and HbV groups. OMP showed impaired action potential duration dispersion (APDd) in the ALB group, whereas normal APDs in HbV and wRBC groups. Lethal arrhythmias were induced by EPS in the ALB group, but not in wRBC and HbV groups. HRV indices, LVEF, Connexin43 were preserved in HbV and wRBC groups. Lethal hemorrhage causes lethal arrhythmias in the presence of impaired APDd. HbV acutely rescues lethal hemorrhage by preventing lethal arrhythmias and preserving arrhythmogenic factors.

Intraosseous infusion of liposome‐encapsulated hemoglobin (HbV) acutely prevents hemorrhagic anemia‐induced lethal arrhythmias, and its efficacy persists with preventing proarrhythmic side effects in the subacute phase of severe hemodilution model

“…For the experimental model creation and study protocol, we used the same method as the previous study 12 except intraosseous infusion line was used in this study, and the survived rats were subjected to the subacute‐phase anti‐arrhythmic evaluation. Sprague‐Dawley rats (male; 8 weeks old; n = 80) were included.…”

“…For preparation of HbV and wRBC were same as the previous report 12 . Briefly, Hb was purified from outdated donated blood provided by the Japanese Red Cross Society (Tokyo, Japan).…”

“…For the preparation of wRBCs, the donor rats for wRBCs were euthanized by brief inhalation anesthesia using isoflurane (>5%). Thereafter, wRBCs were obtained and processed as previously reported 12 …”

“…The blood cell counts and blood gas analysis including pH was performed as same as previous report 12 . Briefly, the actual Hb concentrations in the HbV group were measured using an ABL 80 system analyzer using the conductivity method reported previously.…”

“…In this aspect and beyond the acute resuscitation effect of HbV, a subacute effect and/or a subacute side effect are both important when HbV is applied to clinical use. We previously focused on only acute anti‐arrhythmic efficacy of HbV in the severe hemorrhagic models 12,13 . However, we did not evaluate if the anti‐arrhythmic effect can continue till a subacute phase and we also did not study whether or not a serious proarrhythmic side effect would occur in subacute phase.…”